1. Field of the Invention
The present invention relates generally to the field of stem cells. More particularly, it concerns reprogramming of somatic cells.
2. Description of Related Art
In general, stem cells are undifferentiated cells which can give rise to a succession of mature functional cells. For example, a hematopoietic stem cell may give rise to any of the different types of terminally differentiated blood cells. Embryonic stem (ES) cells are derived from the embryo and are pluripotent, thus possessing the capability of developing into any organ or tissue type or, at least potentially, into a complete embryo.
Induced pluripotent stem cells, commonly abbreviated as iPS cells or iPSCs, are a type of pluripotent stem cells artificially derived from non-pluripotent cells, typically adult somatic cells, by inserting certain genes. Induced pluripotent stem cells are believed to be identical to natural pluripotent stem cells, such as embryonic stem cells in many respects, for example, in the expression of certain stem cell genes and proteins, chromatin methylation patterns, doubling time, embryoid body formation, teratoma formation, viable chimera formation, and potency and differentiability, but the full extent of their relation to natural pluripotent stem cells is still being assessed.
IPS cells were first produced in 2006 (Takahashi et al., 2006) from mouse cells and in 2007 from human cells (Takahashi et al., 2007; Yu et al, 2007). This has been cited as an important advancement in stem cell research, as it may allow researchers to obtain pluripotent stem cells, which are important in research and potentially have therapeutic uses, without the controversial use of embryos.
However, at this stage in the study of these induced pluripotent stem (iPS) cells, the efficiency of generating iPS cells is low, which hurdles the applicability of iPS cells in clinical studies. Therefore, there is a need to develop a method to enhance the efficiency of producing induced pluripotent stem cells.